The Sikorsky R-6 is an American light two-seat helicopter of the 1940s. In

Royal Air Force The Royal Air Force (RAF) is the Air force, air and space force of the United Kingdom, British Overseas Territories and Crown Dependencies. It was formed towards the end of the World War I, First World War on 1 April 1918, on the merger of t ...

and

Royal Navy The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...

service, it was named the Hoverfly II.

Development

The R-6/Hoverfly II was developed to improve on the successful

Sikorsky R-4 The Sikorsky R-4 is a two-seat light helicopter that was designed by Igor Sikorsky with a single, three-bladed main rotor and powered by a radial engine. The R-4 was the world's first large-scale mass production, mass-produced helicopter and the ...

. In order to enhance performance, a completely new streamlined fuselage was designed and the boom carrying the tail rotor was lengthened and straightened. The main rotor and transmission system of the R-4 were retained. Sikorsky allotted their Model 49 designation to the new design. Later, dynamically balanced modifications to the rotor were carried out by Doman Helicopters Inc. The new aircraft could attain compared with by the earlier design. Initial production was by Sikorsky, but most examples were built by

Nash-Kelvinator Nash-Kelvinator Corporation was the result of a merger in 1937 between Nash Motors and Kelvinator Appliance Company. The union of these two companies was brought about as a result of a condition made by George W. Mason prior to his appointment a ...

. Some of the later aircraft were fitted with more powerful engines.

Operational history

The first R-6s were delivered to the

United States Army Air Forces The United States Army Air Forces (USAAF or AAF) was the major land-based aerial warfare service component of the United States Army and ''de facto'' aerial warfare service branch of the United States during and immediately after World War II ...

(USAAF) in late 1944 and some were transferred to the

United States Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

(USN). It was initially intended to pass 150 R-6s to the

(RAF), but delays caused by the switch of production from Sikorsky's factory at

Stratford, Connecticut Stratford is a New England town, town in Fairfield County, Connecticut, United States. It is situated on Long Island Sound at the mouth of the Housatonic River. The town is part of the Greater Bridgeport Planning Region, Connecticut, Greater Bri ...

, to Nash-Kelvinator at

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Michigan Michigan ( ) is a peninsular U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, Upper Midwestern United States. It shares water and land boundaries with Minnesota to the northwest, Wisconsin to the west, ...

, meant that only 27 R-6As were actually delivered to the RAF as the Hoverfly II. Fifteen of these were passed on to the Royal Navy's

Fleet Air Arm The Fleet Air Arm (FAA) is the naval aviation component of the United Kingdom's Royal Navy (RN). The FAA is one of five :Fighting Arms of the Royal Navy, RN fighting arms. it is a primarily helicopter force, though also operating the Lockhee ...

(FAA). Some of the RAF examples were allotted to 657 Squadron RAF for proving the use of helicopters in the Army Co-operation role, and two external stretchers could be fitted to the fuselage. 657 Squadron operated their Hoverfly IIs as Air Observation Posts, spotting for Army artillery units. The Hoverfly IIs remained in operation until April 1951, and one squadron example was displayed at the September 1950

Farnborough Air Show The Farnborough International Airshow is a trade exhibition for the aerospace and defence industries, where civilian and military aircraft are demonstrated to potential customers and investors in Farnborough, Hampshire. Since its first show in ...

. The FAA used their Hoverfly IIs in the training and liaison roles. Naval units to use the type included 771 Squadron from December 1945, followed by 705 Squadron. The USAAF operated their R-6s in secondary roles and the survivors were redesignated H-6A in 1948. The USN examples were designated the HOS-1 and a further 64 were intended to be transferred from the USAAF, but this did not take place. Disposals of surplus military S-49s were made in the civil market in the late 1940s but none now remain in operation. Four are currently displayed in US museums.

Variants

US Navy Sikorsky HOS-1 in flight in January 1947

;XR-6 : prototype powered by a Lycoming O-435-7 (one) ;XR-6A : as XR-6 but powered by the Franklin O-405-9 (five) of which three to the US Navy as XHOS-1 ;YR-6A : as XR-6A with small changes (26) built by Nash-Kelvinator ;R-6A : production model (193) built by Nash-Kelvinator of which 36 to US Navy as HOS-1 and 27 to the RAF as Hoverfly II ;R-6B : projected variant with Lycoming O-435-7, but not proceeded with ;XR-7 : projected development of the XR-6 with a Franklin O-405-9 engine, not built. ;Doman LZ-1 :One R-6A modified as a testbed ;Doman LZ-1A :One R-6A modified as a testbed with a Doman-designed hingeless rotor blades and self-lubricating rotor hub.

Operators

; *

** 162nd Liaison Squadron *

United States Air Force The United States Air Force (USAF) is the Air force, air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its ori ...

** 72nd Liaison Squadron *

United States Coast Guard The United States Coast Guard (USCG) is the maritime security, search and rescue, and Admiralty law, law enforcement military branch, service branch of the armed forces of the United States. It is one of the country's eight Uniformed services ...

; *

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Aircraft on display

* 43-45462 – R-6A on static display at the

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Santa Lucía Air Force Base Num 1 Santa Claus (also known as Saint Nicholas, Saint Nick, Father Christmas, Kris Kringle or Santa) is a legendary figure originating in Western Christian culture who is said to bring gifts during the late evening and overnight hours on Christma ...

. * 43-45473 – R-6A on static display at the

United States Army Aviation Museum The United States Army Aviation Museum is an aviation museum located on Fort Novosel near Daleville, Alabama. It has the largest collection of helicopters held by a museum in the world.Phillips 1992, p. 37.Purner 2004, p. 204. The museum feature ...

Fort Novosel Fort Rucker is a United States Army post located primarily in Dale County, Alabama, United States. It was formerly named in honor of Chief Warrant Officer Michael J. Novosel, an Army aviator and Medal of Honor recipient. It was previously name ...

near

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. * 43-45379 – R-6A on static display at the

National Museum of the United States Air Force The National Museum of the United States Air Force (formerly the United States Air Force Museum) is the official museum of the United States Air Force located at Wright-Patterson Air Force Base, northeast of Dayton, Ohio. The NMUSAF is ...

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. * 43-45480 – LZ-1A on static display at the

New England Air Museum The New England Air Museum (NEAM) is an American aerospace museum located adjacent to Bradley International Airport in Windsor Locks, Connecticut. The museum consists of three display hangars with additional storage and restoration hangars. Its ...

Windsor Locks, Connecticut Windsor Locks is a New England town, town in Hartford County, Connecticut, United States. The town is part of the Capitol Planning Region, Connecticut, Capitol Planning Region. As of the 2020 United States Census, 2020 census, its population was ...

. It was converted by Doman from the R-6. * 43-45531 – R-6 under restoration at the American Helicopter Museum and Education Center in

West Chester, Pennsylvania West Chester is a borough (Pennsylvania), borough and the county seat of Chester County, Pennsylvania, United States. Located in the Delaware Valley, Philadelphia metropolitan area, the borough had a population of 18,671 at the 2020 census. West ...

Specifications (R-6A)

References

Notes

Bibliography

* * * * *

External links

Sikorsky S-49/R-6A/HOS-1/Hoverfly Mk II page at the Sikorsky Archives

Sikorsky R-6A page at the National Museum of the United States Air Force

{{USN helicopters 1940s United States military utility aircraft United States military helicopters 1940s United States helicopters R-006 Single-engined piston helicopters Aircraft first flown in 1943 Single-rotor helicopters Aircraft with fixed conventional landing gear